This invention relates to a platform or vehicle-mounted artillery firing system and in particular to a platform or vehicle-mounted mortar system and improvements in relation thereto.
Traditionally, a mortar system was an infantry and commando weapon that was designed for man-packing. It had to be broken down into a few sub-assemblies to resolve the weight constraint necessitated by man-packing. Therefore, to set up the mortar system for firing will take at least a few minutes. However, mortar systems have now been mounted on various vehicles to meet the quick response required in performing hit-and-run missions demanded in modern warfare.
The traditional mortar system consists of a barrel and breech assembly, bipod assembly and a base-plate. The breech piece has a spherical joint with the base-plate sitting on the ground. The bipod assembly is used for supporting the barrel and for fine adjustment of its elevation and travel. The gas pressure acting on the breech and the reaction force generated during firing, which are subsequently transmitted onto the structure (base-plate) is very high. It could be as high as 150,000 kPa, but it is not a problem for a solid structure such as a base-plate that sits on the ground and acts as a natural damper.
When the mortar system is platform-mounted (in particular when it is mounted on a vehicle), most system integrators currently use the traditional mortar system and focus on designing the structure to withstand the firing force. This will result in heavy structural reinforcement/modification of the mounting platform (vehicle). The damping adapter has been developed by some system integrators as an interface between the mortar and the platform (vehicle) which is able to reduce the firing force to about 40%. However, even with a 60% reduction (60,000 kPa) of the firing force, it is still very large and requires a heavy structure to withstand it. The suspension system also requires reinforcement if the platform (vehicle) is designed to fire on it.
The following problems have been borne in mind when solving the deficiencies, such as lack of recoil buffering and accuracy of the mortar systems of the prior art, and the lack of manoeuverability of the whole vehicle.
The recoil buffer mechanism is the most essential part of the gun system. The traditional mortar system is designed for man-packing and therefore its weight must be relatively lighter to allow portability. Thus the recoil mechanism has never been considered for use in the mortar system. However, when the mortar system is platform-mounted (vehicle-mounted), the recoil forces become more critical compared to the weight of the individual sub-assembly. Hence, some system integrators have incorporated the recoil mechanism to absorb the high recoil force, but this mechanism may not be efficient as the recoiling mass is too low to absorb the firing energy effectively and subsequently convert it to the recoil braking force.
xe2x80x9cOxe2x80x9d-cradle designs, xe2x80x9cUxe2x80x9d-cradle designs and a combination of both are the three most common cradle designs in gun systems that are used for the support and guidance of the recoiling mass during firing.
The xe2x80x9cOxe2x80x9d cradle design is the first-generation gun cradle design. It has two bushes at both ends of the cradle to support and allow the barrel to slide on its outer cylindrical surface when recoiling during firing. It is the simplest in construction and the most commonly-used design. The big and long cylindrical sliding surface on the barrel carries an excessive amount of weight. On the other hand, there are minimum number of parts attached on the recoiling mass, which reduces the effectiveness of the buffering of the recoil.
The xe2x80x9cUxe2x80x9d cradle design is the second-generation gun cradle design. The xe2x80x9cTxe2x80x9d shaped slot on the cradle is used to support and guide the barrel while recoiling during firing. Two brackets are attached onto the barrel (or one on the barrel and one on the breech) as a bridge between the barrel and cradle. The external profile of the barrel can be optimized to achieve the design strength (gas pressure distance profile). Hence, there will be significant weight reduction on the barrel. The recoil cylinder can be attached together with the barrel to increase the recoiling mass to reduce the recoiling force. However, the cradle is complex in both design and manufacturing.
The xe2x80x9cOxe2x80x9d and xe2x80x9cUxe2x80x9d combination cradle design takes advantage of the benefits of both the above designs. Its front support is an xe2x80x9cOxe2x80x9d cradle design and its rear side is a xe2x80x9cTxe2x80x9d cradle design. The cylindrical surface of the barrel on its centre portion is used for front sliding and only one bracket is attached onto either the barrel or on the breech as the rear support. The barrel external profile is very close to an optimized design and it saves one bracket. The cradle is, however, complex in both design and manufacturing. Regardless of all the three types of cradle design, the minimum length of the cradle will be twoxc3x97support length+recoiling length+safety allowance.
To-date, the muzzle brake has not been adopted onto any mortar system. The traditional mortar system is designed to be man-packed. Its weight is very critical. Therefore, the muzzle brake has never been considered for the mortar system.
The bomb muzzle velocity is very much slower than the gas flow when it leaves the barrel. The bomb will be unstable because of gas turbulence at the muzzle. Trying to re-stabilize the flight path of the bomb during flight will result in the bomb losing its kinetic energy and accuracy.
The most common elevating mechanisms used in gun design are the arc and pinion gear design, the single actuator at the centre, or two actuators installed on both sides of the elevating mass in parallel. The base width of these mechanisms is quite small.
The arc and pinion gear or linear actuator are most commonly used for the traversing mechanism. In the arc and pinion mechanism, backlash (clearances) in the gear trains is essential to ensure the smooth running of the mechanism. The acceptable backlash in the traversing mechanism for accurate gun laying demand high precision and costly components. Alternatively, complex anti-backlash mechanisms are normally employed to resolve the problem. Another disadvantage is that the gear teeth have friction due to their relative movements and are prone to wear and tear since it is very difficult to protect against dust and dirt in its operating environment. The uneven wear and tear will cause malfunction of the anti-backlash mechanism after prolonged usage.
The linear actuator is only used in traverse mechanisms having a smaller arc of traverse. Furthermore, it has a non-linear (cosine error) correlation movement between the linear actuator and the rotating action. This will complicate the control system for a closed-loop power drive system.
The invention herein seeks to overcome most of the disadvantages in the prior art mentioned above.
An objective of the invention is to provide a tetrahedron shape for the arrangement of the elevating cylinder avoids causing each member to suffer excessive bending force and the stable shape allows the barrel to move in one plane or in one direction. Therefore, the improved system can be mounted on a much lower class of platform or vehicle (eg. from a 30-tonne vehicle to a 10-tonne vehicle).
According to one aspect of the invention there is provided an elevating apparatus for an artillery gun of the type comprising a breech assembly connected to a barrel, the breech assembly having a firing mechanism for firing a projectile through an open end of the barrel, the elevating apparatus comprising a support means adapted to support the barrel and breech assembly and three connecting members, the support means including three support members two of which include an elevating mechanism for raising and lowering the barrel wherein the three connecting members are disposed in a substantially triangular arrangement, and the three connecting members and the three support members are disposed in a substantially tetrahedral arrangement.
Preferably there are two of said piston and cylinder combinations.
Preferably each said elevating mechanism includes a piston and cylinder combination which is arranged such that relative movement between the piston and cylinder causes the barrel to be raised or lowered. Preferably there are two of said piston and cylinder combinations.
The support means preferably includes a cradle adapted to support the barrel directly or indirectly, wherein at least one of the support members is secured at one end to the cradle and at the other end to a support platform. The piston and cylinder combinations may be secured to the cradle so that it can provide support for the barrel and the breech assembly.
A respective one of said connecting member is desirably connected between the support platform and each of the two said pistons and cylinder combinations, and a third one of the connecting members is a cross-connecting member is desirably connected between said two piston and cylinders.
According to another aspect of the invention there is provided a traversing apparatus for an artillery gun comprising a breech assembly connected to a barrel, the breech assembly having a firing mechanism for firing a projectile through an open end of the barrel, the traversing apparatus comprising; a support platform which is adapted to support the barrel and breech assembly in such a manner that said barrel and breech assembly may rotate relative to the support platform in order to impart a traversing motion to the barrel and breach assembly, the support platform including an arcuate guide member having support means adapted to support the barrel and breech assembly so that the support means follows the guide member during said traversing motion of the barrel and breech assembly; and drive means secured to the support means and adapted to drive movement of the support means along the guide member to cause said traversing motion, wherein the drive means comprises a drive wheel and a drive cable wrapped around the drive means or in connection therewith, the drive cable being substantially fixed relative to the guide member so that rotation of the drive wheel causes the drive wheel and the support means to be driven along the guide member.
The drive cable preferably sits in a recess provided in the drive wheel. The recess in the drive wheel preferably extends around the drive wheel in a substantially helical fashion. The drive cable may extend at least partly around the guide member. It is desirable that tensioning means is provided to maintain the drive cable in tension.
The support means may include at least one support member adapted to support the barrel and the breech assembly. Preferably, the or each support member includes a mechanism for adjusting the elevation of the barrel. Most preferably there are two support members.
In a preferred embodiment, the guide member is provided with a T-shaped recess, and the support means is provided with a formation adapted to engage the recess thereby guiding movement of the support means along the guide member.
According to another aspect of the invention there is provided an elevating apparatus for an artillery gun of the type comprising a breech assembly connected to a barrel, the breech assembly having a firing mechanism for firing a projectile through an open end of the barrel, the elevating apparatus comprising three base members disposed in a substantially triangular arrangement, and three support members arranged to support the artillery gun, wherein at least one of the support members is extendible to vary the elevation of the artillery gun, and wherein the base members and the support members are disposed in a substantially tetrahedral arrangement.
Preferably, two of the support members are extendible. Preferably also, the or each extendible support member comprises a piston and cylinder arrangement.
The elevating apparatus according to this aspect of the invention may also be provided with features of the elevating apparatus described above.
According to another aspect of the invention there is provided an artillery gun comprising a breech assembly connected to a barrel, the breech assembly having a firing mechanism for firing a projectile through an open end of the barrel, wherein the barrel includes a muzzle brake through which projectile propellant gas can escape from the barrel.
According to another aspect of the invention there is provided an artillery gun comprising an elevating apparatus, a recoil buffering apparatus, and a breech assembly connected to a barrel. The breech assembly having a firing mechanism for firing a projectile through an open end of the barrel, and the recoil buffering apparatus comprising a recoil buffering means adapted to be integrated or other wise secured to the barrel and movable therewith during recoil action of the barrel caused by firing of the projectile, and support means associated with the recoil buffering means for supporting the recoil buffering means and thereby supporting the barrel and breech assembly through the recoil buffering means.
The artillery gun according to the invention is preferably platform or vehicle mounted.
As used herein the expression xe2x80x9cartillery gunxe2x80x9d means guns, cannons, howitzers, mortars and the like, which have a calibre of at least 40 mm, preferably above 50 mm.